ᐅ Should You Install a Photovoltaic Battery Storage System or Not?
Created on: 2 Dec 2020 17:42
H
Heidi1965
Our new build is already quite advanced. Next week, 15 photovoltaic modules with a total output of 5.1 kWp will be installed. We are getting a heat pump with a capacity of 5.12 kWh. Initially, a battery storage system was not planned because we wanted to live in the house for at least one year to monitor our electricity consumption patterns, and then potentially add a battery or expand the photovoltaic system later. Now there is a new program that offers a 40% subsidy for battery storage—but only in connection with new builds. That sounds tempting. Should we go for it? What capacity should the battery have at a minimum? The condition is: "The ratio of system output to usable battery storage capacity must be at least 1.2 kWp to kWh of battery storage. Storage capacity exceeding this ratio is not eligible for funding." Have I understood correctly that only a battery with a capacity of 4.25 kWh would be eligible for funding?
Or is this all too small? Just “play equipment”?
Or is this all too small? Just “play equipment”?
R
RotorMotor2 Dec 2020 20:14Which 40% subsidy for storage is this referring to?
Unfortunately, very few storage systems can actually function as an uninterruptible power supply (UPS) when the grid is down or experiences faults, so you are not necessarily more independent with storage than without.
MichaelH82 schrieb:A nice idea!
If you want to be more independent from the grid and have greater self-sufficiency, I would choose a storage system, even if it is not very cost-effective at the moment.
Unfortunately, very few storage systems can actually function as an uninterruptible power supply (UPS) when the grid is down or experiences faults, so you are not necessarily more independent with storage than without.
MichaelH82 schrieb:I fully agree with this.
If you consider the cost/benefit factor and when the system will pay off, then (if it is to be a KFW40+ house) I would choose the storage as small as possible and maximize the roof space.
M
Martial.white3 Dec 2020 03:37Lower Saxony Photovoltaic Incentive.
What I don’t understand, please enlighten me, why install so many modules on the roof? You only get a few cents feed-in tariff after all. It’s not worth it anymore. And a 7 kWp system should easily cover self-consumption, right?
That’s why I thought a storage system is the more sensible investment.
That’s why I thought a storage system is the more sensible investment.
Most electricity is not used at the time when the photovoltaic system produces the most power, but mainly during the off-peak hours (6-9 AM and 4-10 PM). The larger the system, the more electricity you generate during these off-peak hours. As a result, you can use your own electricity during this time.
With the current system costs of about 1,000 euros per kWp (kilowatt peak), this is economically viable even at a feed-in tariff of 7 cents (return on equity about 2.5–3%). The saved self-consumption is essentially a bonus and increases the return accordingly.
With the current system costs of about 1,000 euros per kWp (kilowatt peak), this is economically viable even at a feed-in tariff of 7 cents (return on equity about 2.5–3%). The saved self-consumption is essentially a bonus and increases the return accordingly.
From my own experience, I can say that 1 kWp of solar power to 0.8 kWh of storage is very reasonable.
So, 10 kWp to 8 kWh. Winter is basically lost anyway, and in summer the storage gets full too quickly, no matter the size. Of course, there are also times in summer when the photovoltaic system is too small because it’s cloudy, the storage is empty, and the house consumes 9 kWh. I’ve experienced that.
This topic is far too complex to give advice here.
What is certain is: fill the roof with panels, and a storage capacity of 0.8 kWh to 1 kWh per kWp is generally sufficient.
So, 10 kWp to 8 kWh. Winter is basically lost anyway, and in summer the storage gets full too quickly, no matter the size. Of course, there are also times in summer when the photovoltaic system is too small because it’s cloudy, the storage is empty, and the house consumes 9 kWh. I’ve experienced that.
This topic is far too complex to give advice here.
What is certain is: fill the roof with panels, and a storage capacity of 0.8 kWh to 1 kWh per kWp is generally sufficient.
H
hampshire3 Dec 2020 08:02The question of the cost-effectiveness of an energy storage system fundamentally depends on the assumed charge-discharge cycles. It can be calculated to look good or bad. The discussion has become quite tedious by now.
The battery storage system is worthwhile when used as an intelligent system that integrates existing storage and appliances. The battery absorbs daytime peak loads with self-generated energy and supplies power overnight. Surplus energy is directed to the electric vehicle and the hot water tank. (The latter even extends the heat pump’s lifespan, as it hardly needs to cycle during summer.) Additionally, other appliances can be controlled and operated based on solar yield—such as dryers, hot tubs, or similar devices. This leaves little energy to be fed back into the grid, as the yield is mostly self-consumed. Replacing expensive utility electricity with cheaper self-generated power is a more attractive business model than chasing feed-in tariffs, which nowadays are merely a nice bonus.
Addendum to @zaba: The rule of thumb is good. In addition, make sure the system has a high charge-discharge power capacity. Without that, it’s all nonsense in practice. We are currently transitioning and will have a system with 8kWh storage and 8(!)kW charge-discharge power. That way, it’s possible to cook on an induction stove using self-produced electricity even in the dark, and the heat pump for hot water can remain off for months...
The battery storage system is worthwhile when used as an intelligent system that integrates existing storage and appliances. The battery absorbs daytime peak loads with self-generated energy and supplies power overnight. Surplus energy is directed to the electric vehicle and the hot water tank. (The latter even extends the heat pump’s lifespan, as it hardly needs to cycle during summer.) Additionally, other appliances can be controlled and operated based on solar yield—such as dryers, hot tubs, or similar devices. This leaves little energy to be fed back into the grid, as the yield is mostly self-consumed. Replacing expensive utility electricity with cheaper self-generated power is a more attractive business model than chasing feed-in tariffs, which nowadays are merely a nice bonus.
Addendum to @zaba: The rule of thumb is good. In addition, make sure the system has a high charge-discharge power capacity. Without that, it’s all nonsense in practice. We are currently transitioning and will have a system with 8kWh storage and 8(!)kW charge-discharge power. That way, it’s possible to cook on an induction stove using self-produced electricity even in the dark, and the heat pump for hot water can remain off for months...
Similar topics